SEALS. 77 



dentition being that of animals living as much on vegetable as on 

 animal food. They are wholly plantigrade, and their claws are non- 

 retractile. They are a remarkably homogeneous group, there being 

 but few differences between them other than their relative sizes and 

 the proportions of their teeth. 



Skeletons are mounted of Brown (Ursus arctos) and Polar 

 Bears (U. maritimus), besides" a large series of skulls of different 

 species. 



The second great division of the Carnivores, the Carnivora 

 Pinnipedia, or Seals, is strikingly modified in general form, yet 

 shows clearly its relationship to the Land Carnivores, and especially 

 to the Bears. The skeleton of a typical Seal (fig. 35) is elongate, 

 with a small skull, no clavicles, rudimentary tail, and limbs of 

 which the upper bones are very short, while the hands and feet 

 are long, with five well-developed toes. The hind legs are turned 

 backwards, so that the two soles are opposed to each other when 

 the animal swims, the two together forming a single posterior 

 swimming-paddle. Their action is similar to that of a person 

 propelling a boat with a single oar worked from the stern. 



The skull (see fig. 36) has no postorbital processes, and the 

 posterior teeth are not differentiated in the same way as those of 



Fig. 30. 



Skull of Sea-Leopard (Stenorhynchus). 



the Land Carnivores, there being no specialized sectorial tooth, 

 nor any flat tubercular teeth at the back of the mouth, all the 

 teeth being long and sharp, with the points directed towards the 

 throat, and forming admirable instruments for catching and hold- 



